Weight Overlap
28.8% shared by weight
Guardfolio Research · ETF Overlap
VTI vs VOO: Why Total Market Plus S&P 500 Barely Diversifies
VTI holds over 3,600 US stocks. VOO holds 500. But VTI's top 10 holdings are identical to VOO's top 10 — in the same order, at only slightly lower weights. The extra 3,100 smaller companies in VTI collectively represent less portfolio weight than Apple alone. The pair shares 28.8% overlap by weight, and the sectors are within 1–2 percentage points across every category. In practice, adding one to the other barely changes what drives the portfolio.
Shared Top-10
Identical — same 10 names, same order
Sector Difference
Within 1–2% in every category
Risk Snapshot
ConcentrationHigh
OverlapVery High
CorrelationVery High
DrawdownModerate
Read This As
Two funds, near-identical top holdings, near-identical sectors, same expense ratio. Holding both is mostly doubling the same position — not diversifying it.
Core Insight
VTI's top 10 are VOO's top 10
VTI tracks the CRSP US Total Market Index — all investable US stocks, roughly 3,600 names. VOO tracks the S&P 500 — the 500 largest. Because the US market is cap-weighted, the mega-caps dominate both. Apple, Microsoft, Nvidia, Amazon, Meta, Alphabet (GOOGL and GOOG), Broadcom, Tesla, and Berkshire Hathaway are the top 10 in both funds, in the same order. The 3,100 additional names in VTI each represent a fraction of a percent — together they don't meaningfully change the portfolio's behavior, sector exposure, or drawdown profile.
Overlap Logic
Why "total market" and "S&P 500" are nearly the same portfolio
The S&P 500 represents approximately 80% of US market capitalization. Because both VTI and VOO weight by market cap, the largest companies dominate both funds by definition. VTI's top 10 names represent roughly 28% of the fund. VOO's top 10 represent roughly 36%. The difference in weight is small — both portfolios live and die with the same mega-cap cluster.
The sectors confirm it: VTI has 30.0% in technology, VOO has 31.5% — a 1.5 percentage point difference. Financial services: 13.0% vs 13.5%. Healthcare: 11.5% vs 11.0%. Industrials: 9.0% vs 8.0%. In every single sector, the two funds are within 1–2 percentage points of each other. There is no sector in which one fund is meaningfully different from the other. An investor looking for sector diversification between VTI and VOO will not find it.
Top Holdings Side by Side
Both funds list the same 10 names in the same order
Every name in VTI's top 10 is also in VOO's top 10 — in identical rank order. The only difference is weight: VOO gives slightly more to each name because it holds fewer total stocks.
| # | VTI holding | VTI wt. | VOO wt. |
|---|---|---|---|
| 1 | AAPL — Apple | 6.0% | 7.0% |
| 2 | MSFT — Microsoft | 5.5% | 6.5% |
| 3 | NVDA — Nvidia | 5.0% | 6.0% |
| 4 | AMZN — Amazon | 3.1% | 3.7% |
| 5 | META — Meta | 2.1% | 2.5% |
| 6 | GOOGL — Alphabet A | 1.7% | 2.0% |
| 7 | AVGO — Broadcom | 1.5% | 1.8% |
| 8 | GOOG — Alphabet C | 1.4% | 1.7% |
| 9 | TSLA — Tesla | 1.3% | 1.5% |
| 10 | BRK.B — Berkshire | 1.2% | 1.4% |
Source: Vanguard fund fact sheets · Holdings as of Q1 2026 · Top-10 data from guardfolio ETF dataset
Sector Breakdown
Every sector within 1.5 percentage points
There is no sector where VTI and VOO differ meaningfully. The maximum gap across all 11 GICS sectors is 1.5 points in technology. In six of eleven sectors the difference is 0.5 points or less.
| Sector | VTI | VOO | Diff |
|---|---|---|---|
| Technology | 30.0% | 31.5% | +1.5% |
| Financial Services | 13.0% | 13.5% | +0.5% |
| Healthcare | 11.5% | 11.0% | -0.5% |
| Consumer Discretionary | 11.0% | 10.5% | -0.5% |
| Communication Services | 9.0% | 9.5% | +0.5% |
| Industrials | 9.0% | 8.0% | -1.0% |
| Consumer Staples | 5.0% | 5.5% | +0.5% |
| Real Estate | 3.0% | 2.0% | -1.0% |
| Energy | 3.5% | 3.5% | 0.0% |
| Materials | 2.5% | 2.0% | -0.5% |
| Utilities | 2.5% | 2.5% | 0.0% |
Source: Vanguard fund profiles · Sector data as of Q1 2026
What To Check
Four dimensions that reveal the near-identical exposure
Identical top-10 holdings
Both funds list AAPL, MSFT, NVDA, AMZN, META, GOOGL, AVGO, GOOG, TSLA, and BRK.B in their top 10 — same names, same order, just slightly different weights.
Sector differences under 2%
No sector differs by more than 1.5 percentage points between the two funds. There is no sector-level diversification benefit to holding both.
Small-cap weight is smaller than it sounds
VTI's small-cap tail adds some mid and small-cap exposure, but at market-cap weighting it is diluted to the point where the effective portfolio behavior is still mega-cap driven.
Same expense ratio
Both VTI and VOO charge 0.03% annually. There is no cost argument for holding one over the other, or for holding both — the choice is purely about what exposure you want, and on that dimension they are nearly identical.
The practical test: look at how the two funds have moved in every major market event over the past decade. The correlation between VTI and VOO has historically been above 0.99. Two positions with 0.99 correlation provide almost no risk diversification from each other.
Concrete Example
The small-cap illusion
The most common reason investors hold both VTI and VOO is the belief that VTI adds small-cap exposure while VOO provides large-cap stability — so the pair covers all market segments. The math works against this intuition. VTI's Apple position is roughly 6% of the fund. All of VTI's small-cap holdings combined — thousands of companies — represent perhaps 8–10% of the fund in total. Apple alone as a single position represents more portfolio weight than the entire small-cap universe in VTI.
This is not a flaw in VTI — it is how cap-weighted indexing works. The fund is giving you the market as it actually exists, where a handful of companies represent enormous weight because the market has valued them at enormous scale. But it means the "diversification" from adding the total market fund to an S&P 500 fund is largely theoretical. The portfolio's actual behavior — how it goes up, how it goes down, what sectors it is sensitive to — barely changes.
Interpretation
When does this pair make sense — and when should it be simplified?
For most investors, there is no diversification reason to hold both VTI and VOO simultaneously. VTI already contains all of VOO's holdings. Adding VOO to a VTI portfolio just increases the weight of the S&P 500 component, shifting the combined portfolio slightly more toward large-cap and slightly away from the small-cap tail — the opposite of what most investors assume they are doing.
If the goal is genuine small-cap exposure, a dedicated small-cap fund — such as a Russell 2000 tracker or a small-cap value fund — achieves that more efficiently than layering VOO on top of VTI. If the goal is simply broad US market exposure, either fund alone accomplishes it. The main case for holding both is administrative: an investor may have VTI in one account and VOO in another without the flexibility to consolidate. In that context the overlap is acceptable. But it should be understood as redundancy rather than diversification.
Guardfolio Benchmark
How Guardfolio would frame this pair in a portfolio review
Identical top-10
When two funds share every name in the top 10, the diversification case depends almost entirely on the tail — where each individual holding is a fraction of a percent and has minimal portfolio impact.
Sector difference under 2% everywhere
VTI and VOO are within 1–2% in every sector. This pair provides no sector diversification. A portfolio review would not count these as two separate sector bets.
Same 0.03% expense ratio
At identical cost, the question is purely what different exposure the second fund adds. The honest answer: almost none at the portfolio level where it matters.
Small-cap goal mismatch
If the intent is genuine small-cap exposure, IWM (Russell 2000) or VBR (Vanguard Small-Cap Value) would deliver it directly. Doubling VTI and VOO delivers mostly more large-cap, not more small-cap.
Related Reading